This invention relates to a hydrophilicizing treatment for a surface, usually a surface with underlying metal already bearing a corrosion protective conversion coating. Previously known corrosion protective coatings that do not require the use of chromium during their formation can be combined with the characteristic hydrophilicizing treatment according to this invention to form a high quality and durable hydrophilic surface. After treatment according to this invention, water will have a tendency to spread spontaneously over the surface. The invention is particularly advantageously applicable to provide aluminum evaporators, heat exchangers, and condensers with hydrophilic coatings that have good corrosion resistance and little or no tendency to develop undesirable odors during use.
Although any of the common structural metals can be used in constructing practical heat exchanging surfaces, aluminum and its alloys are among those most often used, because of their high heat conductivity. In heat exchanger surfaces, metals are normally used without any relatively thick protective coating such as a paint or lacquer that would generally be used in other types of equipment made from metals and exposed to corrosive environments, to improve the resistance of the equipment, but any such relatively thick protective coating is avoided in heat exchangers because such a coating would also reduce the efficiency of heat exchange.
During the cooling of hot air, a common use of these heat exchangers, moisture contained as vapor in the hot air condenses and initially forms water drops or beads on the fins of the heat exchanger. If the surface of the heat exchanger fins is not sufficiently hydrophilic, these water beads accumulate on the fin surface and tend to bridge across the small spaces between fins, thereby impeding the air flow between fins and reducing the heat transfer efficiency. The condensed water beads also tend to absorb dust and contaminants in the air, such as carbon dioxide, nitrogen oxides, and sulfur oxides, which can promote corrosion of the underlying aluminum, and because of the capillary forces holding in place water drops that have grown sufficiently large to bridge between adjacent fins, the normal drainage of water away from the fins that would otherwise carry away these absorbed contaminants is substantially reduced. Therefore, the formation of water beads on the fins of an aluminum heat exchanger not only decreases heat transfer efficiency but also can physically damage the exchanger.
In order to achieve a desirable combination of a hydrophilic nature and corrosion resistance on metal, particularly aluminum, surfaces, various coatings and treatments have been tried, but no fully satisfactory result has yet been achieved. A chromate conversion coating without any post-treatment usually has inadequate corrosion resistance and often develops an unpleasant odor and poor hydrophilicity. Silicate coating over a chromate conversion coat has often been used but has not satisfied all users. More recently, biocide protected hydrophilic organic polymer films have been used as post-treatments over chromate conversion coatings. While effective, these have proved to be expensive and difficult to control in some commercial operations.
Major alterative or concurrent objects of the invention are to achieve (i) a combination of adequate hydrophilicity and corrosion resistance, compared with the prior art, while avoiding the use of polluting constituents, and of highly volatile constituents, particularly organic solvents, with potential toxicity or unpleasant odors for workers, in the treatment compositions, (ii) durability of the hydrophilicity under thermal aging and/or practical use, and (iii) avoidance of the development of unpleasant odors during practical use. Other objects will be apparent from the description below.
Except in the claims and the specific examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word xe2x80x9caboutxe2x80x9d in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred, however. Also, unless expressly stated to the contrary: percent, xe2x80x9cparts ofxe2x80x9d, and ratio values are by weight; the term xe2x80x9cpolymerxe2x80x9d includes xe2x80x9coligomerxe2x80x9d, xe2x80x9ccopolymerxe2x80x9d, xe2x80x9cterpolymerxe2x80x9d, and the like; the first definition or description of the meaning of a word, phrase, acronym, abbreviation or the like applies to all subsequent uses of the same word, phrase, acronym, abbreviation or the like and applies, mutatis mutandis, to normal grammatical variations thereof; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; chemical descriptions of neutral materials apply to the materials at the time of addition to any combination specified in the description and/or of generation in situ in a combination by chemical reactions described in the specification, and do not necessarily preclude chemical changes to the materials as a result of unstated reaction in the combination; specification of materials in ionic form means that the materials are supplied to prepare the compositions containing them in the form of soluble substance(s) containing the ions specified and implies the presence in any composition specified to contain ionic materials of sufficient counterions to produce electrical neutrality for the composition as a whole; any counterions thus implicitly specified preferably are selected from among other constituents explicitly specified in ionic form, to the extent possible; otherwise such counterions may be freely selected, except for avoiding counterions that act adversely to an object of the invention.
It has been found that a hydrophilicity can be imparted to a wide variety of surfaces, and a desirable combination of hydrophilicity and corrosion resistance can be achieved on a surface with underlying metal, particularly aluminum and its alloys containing at least 75% by weight of aluminum, by contacting the surface, preferably, if the surface has underlying metal, after this metal has already been supplied with a corrosion protective coating, with an aqueous liquid composition that comprises, preferably consists essentially of, or more preferably consists of, water and:
(A) a sufficient amount of a component of dissolved and/or stably dispersed1 polymers containing xe2x80x94SO3M moieties, where M represents hydrogen, a monovalent cation, or a monovalent fraction of a cation with a valence of two or higher; and, optionally, one or more of the following components:
1i.e., showing no phase separation evident to normal unaided human vision within a period of observation of 100, or preferably 1000, hours. 
(B) a component of one or more dissolved substances which can be made, and preferably actually is made, by dissolving at least one of elemental metals, metal oxides, and metal hydroxides in aqueous phosphoric acid;
(C) a component of pH adjusting substances that are not part of any one of components (A) and (B) as described above; and
(D) an anti-microbial effective amount of at least one anti-microbial agent that is not part of any of components (A) through (C) as described above,
the amount of component (A) being sufficient in a process according to the invention if the specific surface being treated has a smaller spreading contact angle of pure liquid water on the surface after being treated with a composition according to the invention than the same surface had before such treatment; for a composition according to the invention, the amount of component (A) is sufficient if at least one type of surface can be treated with the composition in a process according to the invention so that pure liquid water has a smaller spreading contact angle on the surface after treatment than on the surface before treatment.
One embodiment of the invention is a composition as described above suitable for direct use in imparting hydrophilicity to a surface; such a composition may be described hereinafter as a xe2x80x9cworking compositionxe2x80x9d. Another embodiment of the invention is a concentrate composition, which can be diluted with water to produce a working composition as specified above. A concentrate composition according to this invention preferably comprises from 1.5 to 10, more preferably from 2.5 to 5, or still more preferably from 3.6 to 4.4, times the concentrations of each of the components, except for water, of a working composition.
Still another embodiment of the invention is a process of contacting a surface to be hydrophilicized with a working composition according to the invention as described above. Other embodiments, such as an article of manufacture comprising a surface hydrophilicized according to the invention and an extended process including a simple process according to the invention along with other steps that may be conventional per se, will be apparent from the description below.
Component (A) as defined above preferably is selected from the group consisting of (i) polymers of vinyl sulfonic acid and (ii) polymer molecules that have most, or more preferably all, of the xe2x80x94SO3M moieties directly chemically bonded to an aromatic ring, with the latter more preferred. Any aromatic ring, including those with heteroatoms, is suitable, but for economy and commercial availability, simple phenyl rings are preferred and sulfonated polystyrene is particularly preferred. A sufficient ratio of xe2x80x94SO3M moieties to carbon atoms in the polymers to give the polymer a solubility in water of at least, with increasing preference in the order given, 0.1, 0.3, 0.5, 0.7, 1.0, 2.0, 3.0, or 4.0% is preferred, and more particularly for polymers containing aromatic rings, the ratio of xe2x80x94SO3M moieties to aromatic rings is at least, with increasing preference in the order given, 0.25:1.0, 0.40:1.0, 0.55:1.0, 0.65:1.0, 0.75:1.0, 0.85:1.0, 0.90:1.0, 0.95:1.0, or 0.99:1.0.
Independently of other preferences, the weight average molecular weight of the polymers in component (A) preferably is at least, with increasing preference in the order given, 1000, 3000, 5000, 7000, 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 65,000, or 69,000 and independently preferably is not more than, with increasing preference in the order given, 10,000,000, 5,000,000, 3,000,000, 1,000,000, 800,000, 600,000, 400,000, 300,000, 200,000, 150,000, 120,000, 100,000, 90,000, 85,000, 80,000, 75,000, or 71,000.
Also independently of other preferences, when component (A) is dissolved in water in the course of preparation of an aqueous liquid composition according to this invention, it is preferably added in a form for which xe2x80x9cMxe2x80x9d in the general formula xe2x80x94SO3M represents an alkali metal cation, so that the polymer added is neutral rather than strongly acidic, as it would be if xe2x80x9cMxe2x80x9d in this general formula represented hydrogen instead. For reasons of economy, xe2x80x9cMxe2x80x9d in this general formula most preferably represents sodium.
Preferred sources of component (B) as described above, a component the presence of which is normally highly preferred in an aqueous treatment composition of the invention, may utilize for their anionic and/or unionized parts any of the phosphoric acids in which phosphorus is in its +5 oxidation state, i.e., metaphosphoric acid (HPO3), orthophosphoric acid (H3PO4), pyrophosphoric acid (H4P2O7), or any of the higher condensed phosphoric acids with the general formula H(n+2)PnO(3n+1), where n represents a positive integer with a value of at least three, or any anions derived from any of these acids. It is generally believed that all these acids are in equilibrium with one another in aqueous solutions, with orthophosphoric acid being much the most predominant at low concentrations and temperatures and the more condensed acids (including metaphosphoric acid) becoming important only at high concentrations and temperatures, or when their salts are present in the aqueous solutions along with acid. At least partly for reasons of economy, orthophosphoric acid is generally preferred for use in this invention.
Aqueous solutions of any sufficiently water soluble salts of these phosphoric acid(s) can be used as component (B) in an aqueous liquid composition according to this invention, but, as already briefly noted above, it is preferable to utilize aqueous liquid compositions prepared by dissolving metal oxide(s) and/or hydroxide(s), hereinafter often jointly abbreviated as xe2x80x9c(hydr)oxide(s)xe2x80x9d, in aqueous phosphoric acid solutions rather than solutions of the salts themselves. The preferred treatment solutions are described in this way because it is often possible to obtain transparent and otherwise apparently stable solutions by dissolving metal (hydr)oxide(s) in aqueous solutions of phosphoric acid, even though these apparent solutions are xe2x80x9csupersaturatedxe2x80x9d with respect to the phosphate and/or mono- or di-acid phosphate salt or salts to which their phosphoric acid and metal contents nominally correspond. Although the invention is not to be considered to be limited by any theory, it is believed that these xe2x80x9csupersaturatedxe2x80x9d solutions may contain coordination compounds or other chemical species of unknown structure that are at least part of the reason for their hydrophilicizing properties. Furthermore, it is preferable to dissolve the phosphoric acid(s), followed by the metal (hydr)oxide(s), before addition of any other ingredients except water, in preparing an aqueous liquid composition according to this invention. An aqueous solution formed in this way may then be added to a separately prepared solution containing some or all of the other ingredients to be included in a composition according to the invention, or these ingredients may be added directly to the solution formed by dissolving metal (hydr)oxide(s)in aqueous phosphoric acid.
Preferably the metal (hydr)oxide(s) codissolved with phosphoric acid in an aqueous liquid composition used according to the invention are (hydr)oxide(s) of metals with a valence of at least two, more preferably exactly two. The single most preferred metal is magnesium. When (hydr)oxide(s) of one or more divalent metals are used with orthophosphoric acid as preferred to form component (B) in situ in the course of preparing an aqueous liquid composition according to the invention, the molar ratio of the divalent metal to the phosphorus atoms in the orthophosphoric acid preferably is at least, with increasing preference in the order given, 1.0:5.0, 1.0:4.0, 1.0:3.5, 1.0:3.0, 1.0:2.8, 1.0:2.6, 1.0:2.4, 1.0:2.3, 1.0:2.2, 1.0:2.1, or 1.0:2.05 and independently preferably is not more than 1.0:0.5, 1.0:0.8, 1.0:1.0, 1.0:1.2, 1.0:1.4, 1.0:1.6, 1.0:1.7, 1.0:1.8, 1.0:1.9, or 1.0:1.95. The center of the most preferred range thus corresponds to the metal dihydrogen phosphate salt of the divalent metal.
Independently, at the time of mixing of metal (hydr)oxide(s) with aqueous phosphoric acid in the course of making an aqueous liquid composition according to the invention, the initial concentration of the phosphoric acid(s), measured as the sum of the stoichiometric equivalents as orthophosphoric acid of all phosphoric acid(s) present in which phosphorus is in its +5 valence state, preferably is at least, with increasing preference in the order given, 0.007, 0.011, 0.020, 0.030, 0.040, 0.050, 0.058, 0.064, 0.068, or 0.072 moles of orthophosphoric acid per kilogram of total aqueous liquid composition, this concentration unit, which may be applied to any ingredient of the composition that has a defined mole, being hereinafter usually abbreviated as xe2x80x9cM/kgxe2x80x9d, and independently this concentration value in an aqueous liquid composition according to the invention preferably is not more than, with increasing preference in the order given, 1.5, 1.0, 0.8, 0.6, 0.4, 0.200, 0.160, 0.130, 0.100, 0.090, 0.080, or 0.074 M/kg.
In the course of preparing an aqueous liquid composition according to the invention, if component (B) is used and is prepared in situ as described above, component (A) is preferably added to an aqueous solution containing component (B) before addition of any other ingredients of the composition, except for water.
A working composition according to this invention preferably has a pH value that is at least, with increasing preference in the order given, 3.0, 3.5, 4.0, 4.3, 4.6, 4.9, 5.2, or 5.4 and independently preferably is not more than, with increasing preference in the order given, 9.0, 8.5, 8.0, 7.5, 7.0, 6.5, 6.2, 6.0, 5.8, or 5.6. If a preferred pH value is not achieved by the amounts of components (A) and (B) used in a composition according to the invention, an alkalinizing or acidifying agent, optional component (C), preferably should be added to the composition. A wide variety of suitable agents for this purpose are known to those skilled in the art. If an alkalinizing agent is needed, as is usual when components (A) and (B) have their most preferred chemical characteristics and concentrations, the same chemical type(s) of metal (hydr)oxide(s) as were used to form component (B) in situ in the course of preparation of the composition are preferably used as alkalinizing agents. Any amount of metal (hydr)oxide(s) used for this purpose are not considered part of the metal (hydr)oxide(e) reacted in situ to generate component (B) as described above, for the purpose of determining compliance with any of the preferred molar ratio limits specified above for this in situ reaction.
It has been observed that compositions according to the invention that contain only components (A) through (C) in addition to water are susceptible to the development of fungal infestations from apparently ambient air-borne fungi. Therefore at least a fungicide is normally preferably present in a composition according to the invention as optional component (D). A particularly suitable fungicide is 2-(4-thiazolyl)benzimidazole, which has the special advantage of successful long term use as a medicine for humans and thus is very unlikely to have any unexpected toxicity.
A working composition according to the invention preferably contains, independently for each component specified: component (A) in a concentration that is at least 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 8.5, 9.0, 9.5, or 9.9 parts of component (A) per thousand parts of the total composition by weight, a concentration unit which may apply generally to any other specified material as well as to component (A) and hereinafter is usually abbreviated as xe2x80x9cpptxe2x80x9d, and independently preferably is not more than, with increasing preference in the order given, 100, 75, 50, 30, 25, 22, 19, 16, 14, 13.0, 12.5, 12.0, 11.5, 11.0, 10.5, or 10.1 ppt; component (B) in a concentration that is at least, with increasing preference in the order given, 0.5, 1.0, 1.3, 1.6, 1.9, 2.1, 2.3, 2.5, or 2.7 ppt and independently preferably is not more than, with increasing preference in the order given, 25, 15, 10, 9.0, 8.0, 7.0, 6.0, 5.0, 4.5, 4.0, 3.5, 3.3, 3.1, or 2.9 ppt; and component (D) in a concentration that is at least, with increasing preference in the order given, 0.1, 0.3, 0.5, 0.7, or 0.9 ppt and independently preferably is not more than, with increasing preference in the order given, 5, 3, 2.5, 2.0, 1.8, 1.6, 1.4, 1.2, or 1.0 ppt. All of the preferred upper limits in the preceding parts of this paragraph are preferred primarily for economyxe2x80x94larger concentrations do not improve the results achieved and are more costly. The lower limits are preferred in order to get a strongly hydrophilic surface. The amount of component (C) preferably should be chosen so as to achieve the preferred pH values for the composition that have already been specified above.
For various reasons it is often preferred that compositions according to the invention as defined above should be substantially free from many ingredients used in compositions for similar purposes in the prior art. Specifically, it may be increasingly preferred in the order given, independently for each preferably minimized component noted below, that these compositions, when directly contacted with metal in a process according to this invention, contain no more than 1.0, 0.35, 0.10, 0.08, 0.04, 0.02, 0.01, or 0.001% of each of the following constituents, except to whatever extent such constituents may be part of necessary or optional components of the compositions as specified above: any metallic element with an atomic number higher than 20, except for titanium, zirconium, and hafnium in complex fluoride anions; nitrate and other oxidizing agents (any others being measured as their oxidizing stoichiometric equivalent as nitrate); organic liquids with a boiling point below 120xc2x0 C. at normal atmospheric pressure; and dispersed silica and/or alumina.
After contact is established between the aqueous liquid treatment composition and the surface to be hydrophilicized, the treated surface is dried, preferably without any intermediate rinsing. The surface may be dried simply by exposure to ambient air with a relative humidity of less than 100%, but ordinarily it is preferable to utilize hot air, which may promote some advantageous chemical reaction in the coating as well as definitely speeding the drying process. The temperature at which the coating applied according to this invention is dried preferably is at least, with increasing preference in the order given, 100, 125, 135, 138, 142, 145, or 148xc2x0 C. and independently preferably is not more than, with increasing preference in the order given, 200, 175, 165, 162, 159, 156, 153, or 150xc2x0 C. The amount of carbon, derived at least partly from component (A) in a composition according to the invention and measured as grams of carbon per square meter of surface treated (a unit which may be applied to other materials than carbon and is hereinafter usually abbreviated as xe2x80x9cg/m2xe2x80x9d), that is added-on to the surface after drying during treatment with a composition according to this invention as described above, a value that can readily be determined from surface emission analysis, preferably corresponds to at least, with increasing preference in the order given, 0.05, 0.10, 0.14, 0.18, 0.21, 0.24, or 0.26 g/m2 and independently, primarily for reasons of economy, preferably is not more than, with increasing preference in the order given, 2.0, 1.5, 1.10, 0.80, 0.50, 0.40, 0.32, or 0.28 g/m2. Of course, if the primary treatment applied before treatment with a composition according to this invention also contains carbon, as do the most preferred primary treatments, the carbon emission from the surface treated must be measured both before and after treatment according to this invention in order to determine, by difference between the two values, the add-on amount attributable to treatment with a composition according to this invention.
A hydrophilicizing treatment according to the invention may be applied over any type of surface that is not already completely hydrophilic. A hydrophilicizing treatment according to this invention is generally advantageous when applied over underlying metals that already have conversion coatings according to the teachings of any one of the following U.S. Patents, the disclosures of all of which, except for any part that may be inconsistent with any explicit statement herein, are hereby incorporated herein by reference: U.S. Pat. No. 5,595,611 of Jan. 21, 1997 to Boulos et al.; U.S. Pat. No. 5,551,994 of Sep. 3, 1996 to Schriever; U.S. Pat. No. 5,534,082 of Jul. 9, 1996 to Dollman et al.; U.S. Pat. No. 5,507,084 of Apr. 16, 1996 to Ogino et al.; U.S. Pat. No. 5,498,759 of Mar. 12, 1996 to Nakada et al.; U.S. Pat. No. 5,498,300 of Mar. 12, 1996 to Aoki et al.; U.S. Pat. No. 5,487,949 of Jan. 30, 1996 to Schriever, U.S. Pat. No. 5,472,524 of Dec. 5, 1995; U.S. Pat. No. 5,472,522 of Dec. 5, 1995 to Kawaguchi et al; U.S. Pat. No. 5,452,884 of Oct. 3, 1995; U.S. Pat. No. 5,451,271 of Sep. 19, 1995 to Yoshida et al.; U.S. Pat. No. 5,449,415 of Sep. 19, 1995 to Dolan; U.S. Pat. No. 5,449,414 of Sep. 12, 1995 to Dolan; U.S. Pat. No. 5,427,632 of Jun. 27, 1995 to Dolan; U.S. Pat. No. 5,415,687 of May 16, 1995 to Schriever; U.S. Pat. No. 5,411,606 of May 2, 1995 to Schriever; U.S. Pat. No. 5,399,209 of Mar. 21, 1995 to Suda et al.; U.S. Pat. No. 5,395,655 of Mar. 7, 1995 to Kazuyuki et al.; U.S. Pat. No. 5,391,239 of Feb. 21, 1995 to Boulos; U.S. Pat. No. 5,378,392 of Jan. 3, 1995 to Miller et al.; U.S. Pat. No. 5,366,567 of Nov. 22, 1994 to Ogino et al.; U.S. Pat. No. 5,356,490 of Oct. 18, 1994 to Dolan et al.; U.S. Pat. No. 5,342,556 of Aug. 30, 1994 to Dolan; U.S. Pat. No. 5,318,640 of Jun. 7, 1994 to Ishii et al.; U.S. Pat. No. 5,298,092 of Mar. 29, 1994 to Schriever; U.S. Pat. No. 5,281,282 of Jan 25, 1994 to Dolan et al.; U.S. Pat. No. 5,268,042 of Dec. 7, 1993 to Carlson; U.S. Pat. No. 5,261,973 of Nov. 16, 1993 to Sienkowski et al.; U.S. Pat. No. 5,242,714 of Sep. 7, 1993 to Steele et al.; U.S. Pat. No. 5,143,562 of Sep. 1, 1992 to Boulos; U.S. Pat. No. 5,141,575 of Aug. 25, 1992 to Yoshitake et al.; U.S. Pat. No. 5,125,989 of Jun. 30, 1992 to Hallman; U.S. Pat. No. 5,091,023 of Feb. 25, 1992 to Saeki et al.; U.S. Pat. No. 5,089,064 of Feb. 18, 1992 to Reghi; U.S. Pat. No. 5,082,511 of Jun. 21, 1992 to Farina et al.; U.S. Pat. No. 5,073,196 of Dec. 17, 1991; U.S. Pat. No. 5,045,130 of Sep. 3, 1991 to Gosset et al.; U.S. Pat. No. 5,000,799 of Mar. 19, 1991 to Miyawaki; U.S. Pat. No. 4,992,196 of Feb. 13, 1991 to Hallman; U.S. Pat. No. 4,985,087 of Jan. 15, 1992 to Mori et al.; U.S. Pat. No. 4,966,634 of Oct. 30, 1990 to Saeki et al.; U.S. Pat. No. 4,961,794 of Oct. 9, 1990 to Miyamoto et al.; U.S. Pat. No. 4,956,027 of Sep. 11, 1990 to Saeki et al.; U.S. Pat. No. 4,927,472 of May 22, 1990 to Matsushima et al.; U.S. Pat. No. 4,880,476 of Nov. 14, 1989 to Matsuda et al.; U.S. Pat. No. 4,874,480 of Oct. 17, 1989 to Sonoda et al.; U.S. Pat. No. 4,865,653 of Sep. 12, 1989 to Kramer; U.S. Pat. No. 4,849,031 of Jul. 18, 1989 to Hauffe et al.; U.S. Pat. No. 4,846,897 of Jul. 11, 1989 to Nakagawa et al.; U.S. Pat. No. 4,812,175 of Mar. 14, 1989 to Reghi; U.S. Pat. No. 4,801,337 of Jan. 31, 1989 to Higgins; U.S. Pat. No. 4,756,805 of Jul. 12, 1988 to Terada et al.; U.S. Pat. No. 4,749,418 of Jun. 7, 1988 to Saeki et al.; U.S. Pat. No. 4,722,753 of Feb. 2, 1988 to Zurilla et al.; U.S. Pat. No. 4,717,431 of Jan. 5, 1988 to Knaster et al.; U.S. Pat. No. 4,673,444 of Jun. 16, 1987 to Saito et al.; U.S. Pat. No. 4,668,305 of May 26, 1987 to Dotlman et al.; U.S. Pat. No. 4,650,525 of Mar. 17, 1987 to Yoshida et al.; U.S. Pat. No. 4,617,346 of Mar. 3, 1987 to Prescott; U.S. Pat. No. 4,644,029 of Feb. 17, 1987 to Cable et al.; U.S. Pat. No. 4,643,778 of Feb. 17, 1987 to Donofrio et al.; U.S. Pat. No. 4,637,840 of Jan. 20, 1987 to Fujii et al.; U.S. Pat. No. 4,637,838 of Jan. 20, 1987 to Rausch et al.; U.S. Pat. No. 4,617,068 of Oct. 14, 1986 to King; U.S. Pat. No. 4,596,607 of Jun. 24, 1986 to Huff et al.; U.S. Pat. No. 4,595,424 of Jun. 17, 1986 to Hacias; U.S. Pat. No. 4,565,585 of Jun. 21, 1986 to Matsuda; U.S. Pat. No. 4,559,087 of Dec. 17, 1985 to Jxc3x6ms et al; U.S. Pat. No. 4,509,992 of Apr. 9, 1985 to Higgins; U.S. Pat. No. 4,498,935 of Feb. 12, 1985 to Kent et al.; U.S. Pat. No. 4,496,404 of Jan. 29, 1985 to King; U.S. Pat. No. 4,486,241 of Dec. 4, 1984 to Donofrio; U.S. Pat. No. 4,475,957 of Oct. 9, 1984 to Sander; U.S. Pat. No. 4,433,015 of Feb. 21, 1984 to Lindert; U.S. Pat. No. 4,419,199 of Dec. 6, 1983 to Hauffe et al.; U.S. Pat. No. 4,419,147 of Dec. 6, 1983 to Murakami et al.; U.S. Pat. No. 4,416,705 of Nov. 22, 1983 to Siemund et al.; U.S. Pat. No. 4,389,260 of Jun. 21, 1983 to Hauffe et al.; U.S. Pat. No. 4,385,096 of May 24, 1983 to Wetzel; U.S. Pat. No. 4,281,203 of Apr. 26, 1983 to Reinhold; U.S. Pat. No. 4,370,177 of Jan. 25, 1983 to Frelin et al.; U.S. Pat. No. 4,341,558 of Jul. 27, 1982 to Yashiro et al.; U.S. Pat. No. 4,339,310 of Jul. 13, 1982 to Oda et al.; U.S. Pat. No. 4,338,141 of Jul. 6, 1982 to Senzaki et al.; U.S. Pat. No. 4,338,140 of Jul. 6, 1982 to Reghi; U.S. Pat. No. 4,316,751 of Feb. 23, 1982 to Prescott et al.; U.S. Pat. No. 4,313,769 of Feb. 2, 1982 to Frelin et al.; U.S. Pat. No. 4,311,535 of Jan. 19, 1982 to Yasuhara et al.; U.S. Pat. No. 4,306,917 of Dec. 22, 1981 to Oda et al.; U.S. Pat. No. 4,295,899 of Oct. 20, 1981 to Oppen; U.S. Pat. No. 4,292,096 of Sep. 29, 1981 to Murakami et al.; U.S. Pat. No. 4,287,004 of Sep. 1, 1981 to Murakami et al.; U.S. Pat. No. 4,278,477 of Jul. 14, 1981 to Reinhold; U.S. Pat. No. 4,273,592 of Jun. 16, 1981 to Kelly; U.S. Pat. No. 4,264,378 of Apr. 28, 1981 to Oppen et al.; U.S. Pat. No. 4,220,486 of Sep. 2, 1980 to Matsushima et al.; U.S. Pat. No. 4,191,596 of Mar. 4, 1980 to Doliman et al.; U.S. Pat. No. 4,183,772 of Jun. 15, 1980 to Davis; U.S. Pat. No. 4,174,980 of Nov. 20, 1979 to Howell, Jr. et al.; U.S. Pat. No. 4,169,741 of Oct. 2, 1979 to Lampatzer et al.; U.S. Pat. No. 4,163,679 of Aug. 7, 1979 to Nagae et al.; U.S. Pat. No. 4,153,479 of May 8, 1979 to Ayano et al.; U.S. Pat. No. 4,149,909 of Apr. 17, 1979 to Hamilton; U.S. Pat. No. 4,148,670 of Apr. 10, 1979 to Kelly; U.S. Pat. No. 4,146,410 of Mar. 27, 1979 to Reinhold; U.S. Pat. No. 4,142,917 of Mar. 6, 1979 to Yashiro et al.; U.S. Pat. No. 4,136,073 of Jan. 25, 1979 to Mori et al.; U.S. Pat. No. 4,131,489 of Dec. 26, 1978 to Newhard, Jr.; U.S. Pat. No. 4,108,690 of Aug. 22, 1978 to Heller; U.S. Pat. No. 4,101,339 of Jul. 18, 1978 to Kaneko et al.; U.S. Pat. No. 4,063,968 of Dec. 20, 1977 to Matsushima et al.; U.S. Pat. No. 4,059,452 of Nov. 22, 1977 to Nishijima et al.; U.S. Pat. No. 4,054,466 of Oct. 18, 1977 to King et al.; U.S. Pat. No. 4,017,334 of Apr. 12, 1977 to Matsushima et al.; U.S. Pat. No. 3,989,550 of Nov. 2, 1976 to Newhard; U.S. Pat. No. 3,964,936 of Jun. 22, 1976 to Das; U.S. Pat. No. 3,912,458 of Oct. 4, 1975 to Faigen; U.S. Pat. No. 3,879,237 of Apr. 22, 1975 to Faigen; U.S. Pat. No. 3,876,435 of Apr. 8, 1975 to Doliman; U.S. Pat. No. 3,860,455 of Jan. 14, 1975 to Hansen et al.; U.S. Pat. No. 3,850,700 of Nov. 26, 1974 to Heller; U.S. Pat. No. 3,839,099 of Oct. 1, 1974 to Jones; U.S. Pat. No. 3,819,424 of Jun. 25, 1974 to Russell et al.; U.S. Pat. No. 3,819,422 of Jun. 25, 1974 to Schneider; U.S. Pat. No. 3,819,385 of Jun. 25, 1974 to Schumichen et al.; U.S. Pat. No. 3,759,549 of Mar. 6, 1974 to Matsushima et al.; U.S. Pat. No. 3,758,349 of Sep. 11, 1973 to Engesser; U.S. Pat. No. 3,723,334 of Mar. 27, 1973 to Maurer; U.S. Pat. No. 3,723,192 of Mar. 27, 1973 to Obi et al.; U.S. Pat. No. 3,706,604 of Dec. 19, 1972 to Paxton; U.S. Pat. No. 3,697,332 of Oct. 10, 1972 to Kuehner; U.S. Pat. No. 3,671,332 of Jun. 20, 1972 to Rausch et al.; U.S. Pat. No. 3,660,172 of May 2, 1972 to Otto; U.S. Pat. No. 3,645,797 of Feb. 29, 1972 to Lorin; U.S. Pat. No. 3,632,447 of Jan. 4, 1972 to Albrecht et al.; U.S. Pat. No. 3,625,777 of Dec. 7, 1971 to Okabe et al.; U.S. Pat. No. 3,620,777 of Nov. 16, 1971 to Okabe et al.; U.S. Pat. No. 3,619,300 of Nov. 9, 1971 to Heller et al.; U.S. Pat. No. 3,615,912 of Oct. 26, 1971 to Dittel et at; U.S. Pat. No. 3,615,890 of Oct. 26, 1971 to Montetla; U.S. Pat. No. 3,607,453 of Sep. 21, 1971 to Engesser et at; U.S. Pat. No. 3,573,997 of Apr. 6, 1971 to Paxton; U.S. Pat. No. 3,565,699 of Feb. 23, 1971 to Paxton; U.S. Pat. No. 3,547,711 of Dec. 15, 1970 to Ashdown; U.S. Pat. No. 3,544,388 of Dec. 1, 1970 to Russell; U.S. Pat. No. 3,535,168 of Oct. 20, 1970 to Thompson; U.S. Pat. No. 3,533,859 of Oct. 13, 1970 to Engesser et al.; U.S. Pat. No. 3,519,494 of Jul. 7, 1970 to Engesser et al.; U.S. Pat. No. 3,516,875 of Jun. 23, 1970 to Rausch et at; U.S. Pat. No. 3,515,600 of Jun. 2, 1970 to Jones et al.; U.S. Pat. No. 3,505,129 of Apr. 7, 1970 to Burstein et al.; U.S. Pat. No. 3,501,352 of Mar. 17, 1970 to Shah; U.S. Pat. No. 3,493,441 of Feb. 3, 1970 to Rausch et al.; U.S. Pat. No. 3,493,440 of Feb. 3, 1970 to Ashdown; U.S. Pat. No. 3,484,304 of Dec. 16, 1969 to Beach; U.S. Pat. No. 3,468,724 of Sep. 23, 1969 to Reinhold; U.S. Pat. No. 3,467,589 of Sep. 16, 1969 to Rausch et al.; U.S. Pat. No. 3,462,319 of Aug. 19, 1969 to Campbell; U.S. Pat. No. 3,459,604 of Aug. 5, 1969 to Freeman et al.; U.S. Pat. No. 3,454,483 of Jul. 8, 1969 to Freeman; U.S. Pat. No. 3,450,578 of Jun. 17, 1969 to Siemund et at.; U.S. Pat. No. 3,450,577 of Jun. 17, 1969 to Beach; U.S. Pat. Nos. 3,449,229 and 3,449,222 of Jun. 10, 1969 to Freeman et al.; U.S. Pat. No. 3,444,007 of May 13, 1969 to Maurer et al.; U.S. Pat. No. 3,425,947 of Feb. 4, 1969 to Rausch et al.; U.S. Pat. No. 3,404,046 and U.S. Pat. No. 3,404,044 of Oct. 1, 1968 to Russell et al.; U.S. Pat. No. 3,404,043 of Oct. 1, 1968 to Dell; U.S. Pat. No. 3,397,093 of Aug. 13, 1968 to Oswald et al.; U.S. Pat. No. 3,397,092 of Aug. 13, 1968 to Cavanagh; U.S. Pat. No. 3,397,091 and U.S. Pat. No. 3,397,090 of Aug. 13, 1968 to Russell et at; U.S. Pat. No. 3,385,738 of May 28, 1968 to Russell; U.S. Pat. No. 3,380,858 of Apr. 30, 1968 to Champaneria et al.; U.S. Pat. No. 3,377,212 of Apr. 9, 1968 to Newhard; U.S. Pat. No. 3,347,713 of Oct. 17, 1967 to Lodeseen et al.; U.S. Pat. No. 3,338,755 of Aug. 29, 1967 to Jenkins et al.; U.S. Pat. No. 3,307,980 of Mar. 7, 1967 to Freeman; U.S. Pat. No. 3,297,493 of Jan. 10, 1967 to Blum et al.; U.S. Pat. No. 3,294,593 of Dec. 27,1966 to Wyszomirski et al.; U.S. Pat. No. 3,268,367 of Aug. 23, 1966 to Nelson; U.S. Pat. No. 3,240,633 of Mar. 18, 1966 to Gowman et al.; U.S. Pat. No. 3,222,226 of Dec. 7, 1965 to Maurer et al.; U.S. Pat. No. 3,218,200 of Nov. 16, 1965 to Henricks; U.S. Pat. No. 3,210,219 of Oct. 5, 1965 to Jenkins; U.S. Pat. No. 3,202,551 of Aug. 24, 1965 to Gerischer et al.; U.S. Pat. No. 3,197,344 of Jul. 27, 1965 to Paxton; U.S. Pat. No. 3,185,596 of May 25, 1965 to Schiffman; U.S. Pat. No. 3,161,549 of Dec. 15, 1964 to Kallenbach; U.S. Pat. No. 3,154,438 of Oct. 27, 1964 to Keller et al.; U.S. Pat. No. 3,146,113 of Aug. 25, 1964 to Lantoin; U.S. Pat. Nos. 3,130,086 and 3,130,085 of Apr. 21, 1964 to Otto; U.S. Pat. No. 3,101,286 of Aug. 20, 1963 to Reinhold; U.S. Pat. No. 3,090,710 of May 21, 1963 to Triggle et al.; U.S. Pat. No. 3,046,165 of Jul. 24, 1962 to Halversen et al.; U.S. Pat. No. 3,041,215 of Jun. 26, 1962 to Jenkins et al., U.S. Pat. No. 3,007,817 of Nov. 7, 1961 to Cavanagh et al.; U.S. Pat. No. 2,988,465 of Jun. 13, 1961 to Newhard et al.; U.S. Pat. No. 2,979,430 of Apr. 11, 1961 to Keller et al.; U.S. Pat. No. U.S. Pat. No. 2,967,791 of Jan. 10, 1961 to Halversen; U.S. Pat. No. 2,955,061 of Oct. 4, 1960 to Jenkins et al.; U.S. Pat. No. 2,928,763 of Mar. 15, 1960 to Russell et al.; U.S. Pat. No. 2,902,390 of Sep. 1, 1959 to Bell; U.S. Pat. No. 2,892,884 of Jun. 23, 1959 to Rausch et al.; U.S. Pat. No. 2,882,189 of Apr. 14, 1959 to Russell et al; U.S. Pat. No. 2,868,682 of Jan. 13, 1959 to Dell; U.S. Pat. No. 2,851,385 of Sep. 9, 1958 to Spruance et al.; U.S. Pat. No. 2,840,498 of Jun. 24, 1958 to Logue et al.; U.S. Pat. No. 2,835,617 of May 20, 1958 to Maurer; U.S. Pat. No. 2,832,707 of Apr. 29, 1958 to Rossteutscher; U.S. Pat. No. 2,825,697 of Mar. 4, 1958 to Carroll et al.; U.S. Pat. No. 2,819,193 of Jan. 7, 1958 to Rausch; U.S. Pat. No. 2,813,814 of Nov. 19, 1957 to Goodspeed et al.; U.S. Pat. No. 2,813,813 of Nov. 19, 1957 to Ley et al.; U.S. Pat. No. 2,813,812 of Nov. 19, 1957 to Somers et al.; U.S. Pat. No. 2,809,138 of Oct. 8, 1957 to Wagner et al.; U.S. Pat. No. 2,805,969 of Sep. 10, 1957 to Goodspeed et al.; U.S. Pat. No. 2,800,421 of Jul. 23, 1957 to Goodspeed et al.; U.S. Pat. No. 2,798,829 of Jul. 9, 1957 to Newhard et al.; U.S. Pat. No. 2,796,370 of Jun. 18, 1957 to Ostrander et al.; U.S. Pat. No. 2,769,737 of Nov. 6, 1956 to Russell; U.S. Pat. No. 2,702,768 of Feb. 22, 1955 to Hyams; U.S. Pat. No. 2,692,840 of Oct. 26, 1954 to Bell; U.S. Pat. No. 2,665,231 of Jan. 5, 1954 to Amundsen et al.; U.S. Pat. No. 2,609,308 of Sep. 2, 1952 to Gibson; U.S. Pat. No. 2,591,479 of Apr. 1, 1952 to Ward; 2,438,887 of Mar. 30, 1948 to Spruance, Jr.; U.S. Pat. No. 2,298,280 of Oct. 13, 1942 to Clifford et al.; U.S. Pat. No. 2,210,850 of Aug. 6, 1940 to Curtin; U.S. Pat. No. 2,121,574 of Jun. 21, 1938 to Romig; U.S. Pat. No. 2,120,212 of Jun. 7, 1938 to Curtin; U.S. Pat. No. 1,911,537 of May 30, 1933 to Tanner; U.S. Pat. No. 1,895,968 of Jan. 31, 1933 to Curtin et al.; U.S. Pat. No. 1,651,694 of Dec. 6, 1927 to Green et al.; U.S. Pat. No. 1,525,904 of Feb. 10, 1925 to Allen; U.S. Pat. No. 1,291,352 of Jan. 14, 1919 to Allen; U.S. Pat. No. 1,287,605 of Dec. 17, 1918 to Allen; and U.S. Pat. No. 1,248,053 of Nov. 27, 1917 to Allen.
Hydrophilicizing treatment according to the invention is particularly advantageously applied over conversion coatings formed on aluminum by treatment with acidic aqueous liquid compositions containing at least one of the chemical species HB4, H2SiF6, H2TiF6, H2ZrF6, and the salts of any of these acids. More preferably, the liquid compositions used to form a conversion coating over which a hydrophilicizing treatment according to this invention is applied include at least one of H2TiF6, H2ZrF6, and salts of both of these acids, most preferably H2ZrF6 and its salts. Still more preferably the liquid compositions used to form a conversion coating over which a hydrophilicizing treatment according to this invention is applied also include a polymer of polyhydroxyalkylaminomethylene-substituted poly(vinyl phenol) as described in detail in U.S. Pat. No. 5,068,299, the entire disclosure of which, except for any part that may be inconsistent with any explicit statement herein, is hereby incorporated herein by reference. Most preferred are polymers having the composition resulting from the process and materials described at column 11 lines 47-55 of U.S. Pat. No. 5,068,299. Independently of other preferences, compositions of this most preferred type for forming a conversion coating to be hydrophilicized according to this invention preferably contain a total amount of HB4, H2SiF6, H2TiF6, and H2ZrF6, this total including the stoichiometric equivalent as the corresponding acid of any salts of these acids that may be present and being hereinafter briefly denoted as xe2x80x9ctotal fluoacidxe2x80x9d, such that the ratio by weight of total fluoacid in the conversion coating forming composition to the content of polyhydroxyalkylaminomethylene-substituted poly(vinyl phenol) as described in detail in U.S. Pat. No. 5,068,299 in the same composition is at least, with increasing preference in the order given, 0.02:1.0, 0.05:1.0, 0.08:1.0, 0.11:1.0, 0.13:1.0, 0.15:1.0, 0.17:1.0, 0.19:1.0, or 0.21:1.0 and independently preferably is not more than, with increasing preference in the order given, 2.0:1.0, 1.5:1.0, 1.0:1.0, 0.80:1.0, 0.60:1.0, 0.50:1.0, 0.40:1.0, 0.35:1.0, 0.30:1.0, 0.27:1.0, or 0.24:1.0. Independently, in a process of treatment with such compositions according to the invention, the amount of carbon, from the polymer content of the treatment composition, that is added-on to the surface treated as part of its primary coating is at least, with increasing preference in the order given, 0.04, 0.08, 0.12, 0.18, 0.24, 0.28, 0.30, 0.32, 0.34, or 0.36 g/m2 and independently preferably is not more than, with increasing preference in the order given, 4.0, 3.0, 2.0, 1.0, 0.80, 0.60, 0.55, 0.50, 0.45, or 0.40 g/m2.
The second most preferred chemical type of conversion coatings to be hydrophilicized according to this invention are those described in detail in U.S. Pat. No. 5,356,490 of Oct. 18, 1994 to Dolan et al. and U.S. Pat. No. 5,427,632 of Jun. 27, 1995 to Dolan. The entire disclosures of both of these patents, except for any part that may be inconsistent with any explicit statement herein, are hereby incorporated herein by reference.
As is known to those skilled in the art, before forming any kind of conversion coating on aluminum, it is ordinarily preferred to clean and deoxidize the surface by one of the means known in the art.